RFID, Radio Frequency Identification, employs a small radio marker (RFID chip) which includes an electronic circuit/processor with integrated antenna. The radio marker has a unique identification number. When the radio marker is subjected to a radio signal with a specific frequency, it sends back an echo. A radio antenna intercepts this signal if the radio marker is within range. Further information on location can either be stored in the radio marker or in an external database.
A typical area of application for such a device may be in deployment of seismic nodes on the seabed where nodes require to be located, picked up and then replaced in the same location at a later time with as little deviation as possible.
The prior art comprises solutions such as acoustic position transmitters (transponders) which are deployed on the seabed and where cross bearing is employed to obtain a sufficiently accurate indication of position within the range of the transponders.
From US patent no. US 2006/256652 a device is known for locating seismic nodes by means of acoustic locators.
The most important innovative elements in relation to existing technology are:                Each individual radio marker is programmed and transmits its unique signal        Passive radio markers without batteries are virtually everlasting        It is simple and time-saving to deploy radio markers compared to acoustic transponders        Radio markers can be permanently installed down in the seabed without the risk of being damaged by fishing tackle such as trawls and trawl doors        If offers the possibility of integration with sensors        